Primer is primer, paint is paint, and a hack is a hack. Talk to a real
pant store for products, Sherwin Williams is well known and may have a
one coat product. Any painter who says he will mix 2 products not
already offered to make a "Better" product should not be trusted. I
would not let him do the work unless I was there and knew he wasnt doing
other things wrong, you need to learn. Get to a real paint store and
find out what is offered and how to prep and paint correctly.